Each DSPARB register can house bits for two separate pipes, hencewe must protect the registers during reprogramming so that parallelFIFO reconfigurations happening simultaneosly on multiple pipes won'tcorrupt each others values.

We'll use a new spinlock for this instead of the wm_mutex since we'llhave to move the DSPARB programming to happen from the vblank evadecritical section, and we can't use mutexes in there.